Psion has dominated the palmtop market for most of this decade with its Series 3 range, and there weren't really any keyboard-based devices to touch them until the recent launch of systems using Microsoft's Windows CE operating system. Now, Psion is hitting back with its own successor.

The Series 5 doesn't look too different on the outside, but this belies the radical new hardware inside. Previous models were based on a very similar chip to that used in the first PC, whereas the new one uses a 32bit ARM 7100 Risc processor operating at 18.432MHz. This chip is a good choice for a mobile since it consumes very little power, yet packs a processing punch to rival a 486. Coupled with this is 4Mb or 8Mb of memory, and it runs a new operating system called EPOC 32. The Psion SSDs have now been abandoned, with the Series 5 having a single slot for CompactFlash modules, which are an industry standard. There's also an infra-red port, for printing and exchanging files with a PC or another Series 5.

At 354g (12.5oz), the new Psion is slightly heavier and larger than the Series 3 models. It will still fit easily into a jacket pocket, although you will definitely notice its presence. It keeps the familiar clamshell design, although the rotating hinge has gone. Now, when you lift the lid, the keyboard slides forward, allowing the screen to tilt right back to a comfortable viewing angle. The keyboard itself has proper keycaps and though we found the typing action a little stiff, it's fine for text entry.

The screen almost fills the lid, and now boasts a resolution of 640x240 pixels. There's a multiple level zoom facility if text is too small for you, and also a backlight. The screen is also touch-sensitive, so you can use the supplied stylus like you would a mouse, selecting objects or drawing onto it. The application icons are now at the bottom of the screen, and there are special buttons up the left-hand edge, including the zoom facility and one which brings up context-sensitive menus.

Built-in applications are similar to those of the Series 3. Word, Sheet, Data, Agenda, Calc and Time are the word processor, spreadsheet, database, dairy, calculator and world clock, respectively. In addition, there's a spell checker, a terminal program called Comms, a game (Bombs), and Record. The latter lets you record sounds using the microphone on the right-hand side of the case, and play them back through the small speaker at the rear. Record also works with the Psion 5 closed up, thanks to three buttons on the front edge of the case. You hold the Psion edge-on, like a dictaphone, operating the buttons with your thumb.

All of the built-in applications seem as fully-featured as those on a desktop PC. For example, you can embed a file from one app within another, just like Windows OLE, so a Word document can contain an embedded voice message. Using the serial cable and PsiWin 2.0 program, you can also exchange files easily with a PC. Running on Windows 95 or NT 4.0, PsiWin lets you browse the contents of your Series 5, and copy files to or from it. Files are automatically converted during copying, so a Psion Word file can be converted to a Word 7.0 file if you have Office 95. PsiWin also lets you synchronise Psion's Agenda files with Lotus Organizer or Schedule+ diary entries, and there's an upgrade tool to convert Series 3, Series 3a, Series 3c and Siena files to Series 5 format.

There are one or two quibbles about the Series 5, such as the battery compartment feeling a little fragile. The battery life is also reduced to around 30 hours on-time, which will be reduced further if you use the backlight a lot. Overall, however, this is a worthy successor to the Series 3 range.

Daniel Robinson

Verdict The Series 5 combines a wide range of useful applications with an interesting user interface and a much improved keyboard. Its software isn't compatible with the old Series 3, 3a, 3c and Siena, and it only has around half of their battery life. But the Series 5 is more responsive and easier to use than rival Windows CE models and the inclusion of PsiWin and the PC docking cable makes it good value. In our opinion, this is the best palmtop available.